buildtest: add a dedicate crate for process-lines

This will speed up running tests, as it will be possible to run
process-lines in parallel with hello-world.

Author: pietroalbini

tests/buildtest/crates/process-lines/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "process-lines"
+version = "0.1.0"
+authors = ["Pietro Albini <pietro@pietroalbini.org>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

tests/buildtest/crates/process-lines/src/main.rs

@@ -0,0 +1,4 @@
+fn main() {
+    println!("Hello, world!");
+    println!("Hello, world again!");
+}

tests/buildtest/mod.rs

@@ -28,7 +28,7 @@ fn test_hello_world() {
 
 #[test]
 fn test_process_lines() {
-    runner::run("hello-world", |run| {
+    runner::run("process-lines", |run| {
         run.build(SandboxBuilder::new().enable_networking(false), |build| {
             let storage = rustwide::logging::LogStorage::new(LevelFilter::Info);
             let mut ex = false;